/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.tsfile.read.query.timegenerator.node;

import org.apache.iotdb.tsfile.read.common.BatchData;
import org.apache.iotdb.tsfile.read.reader.IBatchReader;

import java.io.IOException;

public class LeafNode implements Node {

    private IBatchReader reader;

    private BatchData cacheData;
    private boolean hasCached;

    private long cachedTime;
    private Object cachedValue;

    public LeafNode(IBatchReader reader) {
        this.reader = reader;
    }

    @Override
    public boolean hasNext() throws IOException {
        if (hasCached) {
            return true;
        }
        if (cacheData != null && cacheData.hasCurrent()) {
            cachedTime = cacheData.currentTime();
            cachedValue = cacheData.currentValue();
            hasCached = true;
            return true;
        }
        while (reader.hasNextBatch()) {
            cacheData = reader.nextBatch();
            if (cacheData.hasCurrent()) {
                cachedTime = cacheData.currentTime();
                cachedValue = cacheData.currentValue();
                hasCached = true;
                return true;
            }
        }
        return false;
    }

    @Override
    public long next() throws IOException {
        if ((hasCached || hasNext())) {
            hasCached = false;
            cacheData.next();
            return cachedTime;
        }
        throw new IOException("no more data");
    }

    /**
     * Check whether the current time equals the given time.
     *
     * @param time the given time
     * @return True if the current time equals the given time. False if not.
     */
    public boolean currentTimeIs(long time) {
        return cachedTime == time;
    }

    /**
     * Function for getting the value at the given time.
     */
    public Object currentValue() {
        return cachedValue;
    }

    @Override
    public NodeType getType() {
        return NodeType.LEAF;
    }
}
